The pthread_barrierattr_destroy function shall destroy a
barrier attributes object. A destroyed attr attributes object
can be reinitialized using pthread_barrierattr_init ; the
results of otherwise referencing the object after it has been
destroyed are undefined. An implementation may cause
pthread_barrierattr_destroy to set the object referenced by
attr to an invalid value.

The pthread_barrierattr_init function shall initialize a
barrier attributes object attr with the default value for all
of the attributes defined by the implementation.

Results are undefined if pthread_barrierattr_init is called
specifying an already initialized attr attributes object.

After a barrier attributes object has been used to initialize one
or more barriers, any function affecting the attributes object
(including destruction) shall not affect any previously initialized
barrier.

Portions of this text are reprinted and reproduced in electronic
form from IEEE Std 1003.1, 2003 Edition, Standard for Information
Technology -- Portable Operating System Interface (POSIX), The Open
Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the
Institute of Electrical and Electronics Engineers, Inc and The Open
Group. In the event of any discrepancy between this version and the
original IEEE and The Open Group Standard, the original IEEE and The
Open Group Standard is the referee document. The original Standard
can be obtained online at http://www.opengroup.org/unix/online.html
.